Abrasive article with replicated microstructured backing and method of using same

ABSTRACT

An abrasive article is provided that includes a flexible backing having opposed first and second major surfaces. The first major surface includes a plurality of abrasive particles in at least one binder disposed thereon. The second major surface includes replicated microstructures having recesses. The abrasive article also includes adhesive contained substantially in the recesses of the replicated microstructures. A rigid substrate can be in contact with at least a portion of the replicated microstructures. Also provide is a method of polishing a work-piece that uses the provided articles.

FIELD

The present disclosure relates to abrasive articles useful for polishingcomplex materials.

BACKGROUND

Work pieces, such as read/write heads for the hard disk drive (HDD)industry, have very hard and very soft, complex materials that aretypically finished simultaneously by lapping and polishing with abrasivearticles. The very soft materials that make up the read/write transducerare located at the edge of the very hard material, such as aluminatitania carbide (AlTiC). Because high pressures are required to removethe hard AlTiC material, pressures of up to 40 pounds per square inch(psi) are applied. High loads on the work-piece can cause a displacementof the abrasive surface if the abrasive matrix is of sufficiently lowmodulus. This can result in a build up of abrasive material at the edgesof the work-piece. The excess abrasive at the edge of the work-piece cancause accelerated removal of the edges or what is commonly called“crown” or “edge roll off”. This crowning effect can damage a transducerthat lies at the edge of the work-piece. Multilayer abrasive articleshaving compliant pressure sensitive adhesives can exacerbate thecrowning of a read/write head.

FIG. 1 is an illustration of a typical prior art system of an abrasivearticle 10 having abrasive particles 12 dispersed in binder 13 (formingan abrasive layer) on first major surface 18 a of flexible backing 18having adhesive layer 14 coated on second major surface 18 b of theabrasive article. The adhesive layer, such as, e.g., a pressuresensitive adhesive layer, secures the abrasive article to rigid support22. When comparing the various components in the abrasive article 10,the adhesive layer is softer (i.e., having a lower Young's modulus) thanthe flexible backing and the abrasive particles.

As shown in FIGS. 1 and 2, in use, typically work-piece 20 is exposed toan abrasive layer (that includes abrasive particles 18 a and binder 13)under a load P. Under such circumstances, the work piece and the loadapplied thereon deform relatively soft adhesive layer 14. The contoursof flexible substrate 18 and abrasive layer 13 tend to follow thedeformation of the adhesive layer causing rounding or crowning of theedges of the work-piece. Additionally, high stresses at the edges ofwork-piece 20, may also cause rounding of the work-piece edges.

SUMMARY

There is a need for solutions to the problem of crowning on work-piecesto be polished—particularly for work-pieces useful in sensitiveelectronics industries such as read-write heads for hard disk drives orthin hard disk drives, themselves. The abrasive articles and methodspresented herein have the benefit of long use life, easy removal ofmaterial from the work-piece, ability to polish to a fine finish, andhigh removal rates. Additionally, they resist crowing of the edges ofthe work-pieces and produce a more desirable product.

In one aspect, an abrasive article is provided that includes a flexiblebacking having opposed first and second major surfaces, an abrasivelayer comprising a plurality of abrasive particles retained in at leastone binder, the abrasive layer disposed on the first major surface ofthe flexible backing, wherein at least a portion the second majorsurface of the flexible backing includes replicated microstructureshaving recesses, and an adhesive, wherein the adhesive is containedsubstantially in the recesses of the replicated microstructures. Thearticle can further include a rigid substrate in contact with at least aportion of the replicated microstructures or a release liner in contactwith at least a portion of the adhesive. The flexible backing can have aYoung's modulus of greater than about 0.5 gigapascals (GPa) or evengreater than 2 GPa, and can include rods, triangles, pyramids, truncatedpyramids, cones, truncated cones, spheres, or spheroids among otherpossible shapes.

In another aspect, a method of polishing is provided that includesproviding a work-piece, contacting the work-piece with an abrasivearticle that includes a flexible backing having opposed first and secondmajor surfaces, an abrasive layer comprising a plurality of abrasiveparticles retained in at least one binder, the abrasive layer disposedon the first major surface of the flexible backing, wherein at least aportion the second major surface of the flexible backing includesreplicated microstructures having recesses, an adhesive; and a rigidsubstrate in contact with at least a portion of the replicatedmicrostructures, wherein the adhesive is contained substantially in therecesses of the replicated microstructures and moving the abrasivearticle relative to the work-piece. The abrasive article is movedrelative to the work-piece thereby polishing a surface of thework-piece. Typically, a load is applied to the work-piece.

The provided abrasive articles and methods are useful for polishingwork-pieces that need to be very smooth and level across theirdimensions. Flexible backings that include replicated microstructuresallow a load that can be applied to the work-piece to be supported by arigid substrate during polishing. The replicated microstructures bearpart of the load, transferring at least part of the load to the rigidsubstrate, thereby reducing or eliminating adhesive deformation. Theadhesive is substantially contained in the recesses of the replicatedmicrostructures allowing direct contact of the replicatedmicrostructures with the rigid substrate. The provided abrasive articlesand methods allow for a finished work-piece having superior flatnessthat, in turn, provides the abrasive articles with the benefits of longlife, easy application, easy removal, fine finish, and high removalrates with an advance over the art of reduced crowning.

The above summary is not intended to describe each disclosed embodimentof every implementation of the present invention. The brief descriptionof the drawings and the detailed description which follows moreparticularly exemplify illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure can be further defined with reference to thefigures, wherein:

FIG. 1 is a schematic cross-section of a prior art abrasive system;

FIG. 2 is a schematic cross-section of the prior art abrasive system ofFIG. 1 where a load has been applied to a work-piece;

FIG. 3 is a schematic cross-section of an embodiment of a providedabrasive article wherein the replicated microstructures are a part ofthe second surface of the flexible backing and include pyramids orpyramidal ridges;

FIG. 4 is a schematic cross-section of an embodiment of a providedabrasive article wherein the replicated microstructures are structurallyattached to the second surface of the flexible backing and includepyramids or pyramidal ridges;

FIG. 5 is a schematic cross-section of another embodiment of a providedabrasive article wherein the replicated microstructures includetruncated pyramids or pyramidal ridges; and

FIG. 6 is a schematic cross-section of yet another embodiment of aprovided abrasive article wherein the replicated microstructures includesquare ridges.

FIG. 7 is a cross-sectional view of a microstructured roll surface usedin an exemplary embodiment of the provided abrasive article.

FIG. 8 is a cross-sectional or cross-web view of an exemplary backingmicrostructure produced using the microstructured roll surface in FIG.7.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanying setof drawings that form a part of the description hereof and in which areshown by way of illustration several specific embodiments. It is to beunderstood that other embodiments are contemplated and may be madewithout departing from the scope or spirit of the present invention. Thefollowing detailed description, therefore, is not to be taken in alimiting sense.

Unless otherwise indicated, all numbers expressing feature sizes,amounts, and physical properties used in the specification and claimsare to be understood as being modified in all instances by the term“about.” Accordingly, unless indicated to the contrary, the numericalparameters set forth in the foregoing specification and attached claimsare approximations that can vary depending upon the desired propertiessought to be obtained by those skilled in the art utilizing theteachings disclosed herein. The use of numerical ranges by endpointsincludes all numbers within that range (e.g. 1 to 5 includes 1, 1.5, 2,2.75, 3, 3.80, 4, and 5) and any range within that range.

Flexible Backing

The provided abrasive articles and methods include a flexible backinghaving opposed first and second major surfaces. Suitable flexiblebackings that can be used in the provided abrasive articles aretypically those known in the abrasive art. They include polymericsubstrates, e.g. polyester, polycarbonate, polypropylene, polyethylene,cellulose, polyamide, polyimide, polysilicone, andpolytetrafluoroethylene; metal foils including aluminum, copper, tin andbronze; and papers, including densified kraft paper and poly-coatedpaper.

The material of the flexible backing includes replicated microstructureson at least a portion of its second major surface. In some embodiments,a separate backing that includes a replicated microstructure can beselected to provide an abrasive construction that exhibits uniformmaterial removal across the work-piece, i.e., good uniformity andplanarity which includes flatness. It is important that the materialproperties of the flexible backing and the replicated microstructurefeatures contained thereon have material properties that allow thesurface of a work-piece to be smooth across all of itsdimensions—particularly at the edges of the work-piece.

Abrasive Layer

The provided abrasive articles include an abrasive layer comprising aplurality of abrasive particles retained in at least one binder, theabrasive layer disposed on the first major surface of the flexiblebacking, wherein at least a portion the second major surface of theflexible backing includes replicated microstructures having recesses.Suitable abrasive particles that can be used in the provided articlesand methods include fused aluminum oxide, heat treated aluminum oxide,white fused aluminum oxide, black silicon carbide, green siliconcarbide, titanium diboride, boron carbide, tungsten carbide, titaniumcarbide, diamond (both natural and synthetic, including polycrystallinediamond), silica, iron oxide, chromia, ceria, zirconia, titania,silicates, tin oxide, cubic boron nitride, garnet, fused aluminazirconia, sol gel abrasive particles and the like. Examples of sol gelabrasive particles can be found in U.S. Pat. Nos. 4,314,827 (Leitheiseret al.); 4,623,364 (Cottringer et al); 4,744,802 (Schwabel); 4,770,671(Monroe et al.) and 4,881,951 (Wood et al.).

As used herein, the term abrasive particle also encompasses singleabrasive particles bonded together with a polymer, a ceramic, a metal ora glass to form abrasive agglomerates. The term abrasive agglomerateincludes, but is not limited to, abrasive/silicon oxide agglomeratesthat may or may not have the silicon oxide densified by an annealingstep at elevated temperatures. Abrasive agglomerates are furtherdescribed in U.S. Pat. Nos. 4,311,489 (Kressner); 4,652,275 (Bloecher etal.); 4,799,939 (Bloecher et al.), 5,500,273 (Holmes et al.), 6,645,624(Adefris et al.); 7,044,835 (Mujumdar et al.). Alternatively, theabrasive particles may be bonded together by inter-particle attractiveforces as describe in U.S. Pat. No. 5,201,916 (Berg et al.). Typicalabrasive agglomerates include agglomerates having diamond as theabrasive particle and silicon oxide as the bonding component. When anagglomerate is use, the size of the single abrasive particle containedwithin the agglomerate can range from 0.1 to 50 micrometer (μm) (0.0039to 2.0 mils), preferably from 0.2 to 20 μm (0.0079 to 0.79 mils) andmost preferably between 0.5 to 5 μm (0.020 to 0.20 mils).

The average particle size of the abrasive particles can be less than 150μm (5.9 mils), typically less than 100 μm (3.9 mils), or even less than50 μm (2.0 mils). The size of the abrasive particle is typicallyspecified to be its longest dimension. Typically, there will be a rangedistribution of particle sizes. In some instances, the particle sizedistribution can be tightly controlled such that the resulting abrasivearticle provides a consistent surface finish on the work piece beingabraded.

Yet another useful type of abrasive particle is a metal-based abrasiveparticle having a substantially spheroid metal containing matrix havinga circumference and a super-abrasive materials having an averagediameter of less than 50 μm, preferably less than 8 μm, at leastpartially embedded in the circumference of the metal containing matrix.Such abrasive particles can be made by charging into a vessel,metal-containing matrix (predominantly spheroids), super-abrasiveparticles, and grinding media. The vessel can then be then rolled for aperiod of time, typically at room temperature. Although not being boundby theory, it is believed that the milling process forces the superabrasive material to penetrate into, attach to, and protrude from themetal containing matrix. The circumference of the metal containingmatrix changes from pure metal or metal alloy to a composite of superabrasive and metal or metal alloy. The subsurface of the metalcontaining matrix near the circumference also contains the superabrasive material, which would be considered as being embedded in themetal containing matrix. This metal-based abrasive particle is disclosedin assignee's co-pending U.S. Pat. App. Pub. No. 2010/0000160 (Lugg etal.).

Abrasive particles can be coated with materials to provide the particleswith desired characteristics. For example, materials applied to thesurface of an abrasive particle have been shown to improve the adhesionbetween the abrasive particle and the binder. Additionally, a materialapplied to the surface of an abrasive particle may improve the adhesionof the abrasive particles when a softened particulate curable bindermaterial is used as the binder. Alternatively, surface coatings canalter and improve the cutting characteristics of the resulting abrasiveparticle. Such surface coatings are described, for example, in U.S. Pat.Nos. 5,011,508 (Wald et al.); 3,041,156 (Rowse et al.); 5,009,675 (Kunzet al.); 4,997,461 (Markhoff-Matheny et al.); 5,213,591 (Celikkaya etal.); 5,085,671 (Martin et al.) and 5,042,991 (Kunz et al.).

Provided abrasive articles and methods can include conventional coatedabrasive articles, coatings (make coat, size coat and super size coat)and materials. Exemplary coated abrasive articles are described in U.S.Pat. No. 5,378,252 (Follensbee), U.S. Pat. No. 5,834,109 (Follett et.al.) and U.S. Pat. No. 6,979,713 (Barber). Provided abrasive articlesand methods can include abrasive coatings that are shaped or structured.By shaped or structured it is meant that the abrasive coating has raisedportions and recessed portions. Exemplary abrasive articles that includeshaped or structured abrasive coatings are available under the tradedesignation TRIZACT from 3M Company, St. Paul, Minn. They are generallydescribed in U.S. Pat. No. 5,152,917 (Pieper et al.). Other lappingmaterials useful as abrasive articles in the provided abrasive articlesand methods are also described in U.S. Pat. No. 5,489,235 (Gagliardi etal.).

The abrasive particles can be partially embedded into the first opposingsurface of the flexible backing and can be held in place by the flexiblebacking. The abrasive articles can also be bonded to the flexiblebacking by thermal bonding, ultrasonic welding, or microwave-activatedbonding. Alternatively, a binder can be used to hold the abrasiveparticles onto the first surface of the flexible backing. Useful bindersfor holding abrasive particles onto the first surface of the flexiblebacking are well known to those of ordinary skill in the art andadhesives.

Suitable binder precursors are typically, in an uncured or uncrosslinkedstate, flowable at or near ambient conditions. The binder precursor isthen typically exposed to conditions (typically an energy source) thatat least partially cure or crosslink (i.e., free-radical polymerization)the binder precursor, thereby converting it into a binder capable ofretaining the dispersed abrasive particles. Exemplary energy sourcesinclude: e-beam, ultraviolet radiation, visible radiation, infraredradiation, gamma radiation, heat, and combinations thereof.

Useful poly(meth)acrylates include monomers and/or oligomers that haveat least two (meth)acrylate groups; for example, tri(meth)acrylates, andtetra(methacrylates). Exemplary poly(methacrylates) include:di(meth)acrylates such as, for example, 1,3-butylene glycoldi(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanedioldi(meth)acrylate, 1,6-hexanediol mono(meth)acrylate mono(meth)acrylate,ethylene glycol di(meth)acrylate, alkoxylated aliphaticdi(meth)acrylate, alkoxylated cyclohexanedimethanol di(meth)acrylate,alkoxylated hexanediol di(meth)acrylate, alkoxylated neopentyl glycoldi(meth)acrylate, caprolactone modified neopentyl glycol hydroxypivalatedi(meth)acrylate, caprolactone modified neopentyl glycol hydroxypivalatedi(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, diethyleneglycol di(meth)acrylate, dipropylene glycol di(meth)acrylate,ethoxylated (10) bisphenol A di(meth)acrylate, ethoxylated (3) bisphenolA di(meth)acrylate, ethoxylated (30) bisphenol A di(meth)acrylate,ethoxylated (4) bisphenol A di(meth)acrylate, hydroxypivalaldehydemodified trimethylolpropane di(meth)acrylate, neopentyl glycoldi(meth)acrylate, polyethylene glycol (200) di(meth)acrylate,polyethylene glycol (400) di(meth)acrylate, polyethylene glycol (600)di(meth)acrylate, propoxylated neopentyl glycol di(meth)acrylate,tetraethylene glycol di(meth)acrylate, tricyclodecanedimethanoldi(meth)acrylate, triethylene glycol di(meth)acrylate, tripropyleneglycol di(meth)acrylate; tri(meth)(meth)acrylates such as glyceroltri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylatedtri(meth)acrylates (e.g., ethoxylated (3) trimethylolpropanetri(meth)acrylate, ethoxylated (6) trimethylolpropane tri(meth)acrylate,ethoxylated (9) trimethylolpropane tri(meth)acrylate, ethoxylated (20)trimethylolpropane tri(meth)acrylate), pentaerythritoltri(meth)acrylate, propoxylated tri(meth)acrylates (e.g., propoxylated(3) glyceryl tri(meth)acrylate, propoxylated (5.5) glyceryltri(meth)acrylate, propoxylated (3) trimethylolpropanetri(meth)acrylate, propoxylated (6) trimethylolpropanetri(meth)acrylate), trimethylolpropane tri(meth)acrylate,tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate; and higherfunctionality (meth)acryl containing compounds such asditrimethylolpropane tetra(meth)acrylate, dipentaerythritolpenta(meth)acrylate, ethoxylated (4) pentaerythritoltetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, caprolactonemodified dipentaerythritol hexa(meth)acrylate; oligomeric (meth)acrylcompounds such as, for example, polyester (meth)acrylates, epoxy(meth)acrylates; and combinations thereof. Such compounds are widelyavailable from vendors such as, for example, Sartomer Co. of Exton, Pa.;UCB Chemicals Corporation of Smyrna, Ga.; and Aldrich Chemical Companyof Milwaukee, Wis.

The binder precursor may comprise an effective amount of at least onephotoinitiator; for example, in an amount of from 0.1, 1, or 3 percentby weight, up to 5, 7, or even 10 percent by weight, or more. Usefulphotoinitiators include those known as useful for free-radicallyphotocuring (meth)acrylates. Exemplary photoinitiators include benzoinand its derivatives such as alpha-methylbenzoin; alpha-phenylbenzoin;alpha-allylbenzoin; alpha-benzylbenzoin; benzoin ethers such as benzildimethyl ketal (available as IRGACURE 651 from Ciba Specialty Chemicals,Tarrytown, N.Y.), benzoin methyl ether, benzoin ethyl ether, benzoinn-butyl ether; acetophenone and its derivatives such as2-hydroxy-2-methyl-1-phenyl-1-propanone (available as DAROCUR 1173 fromCiba Specialty Chemicals) and 1-hydroxycyclohexyl phenyl ketone(available as IRGACURE 184 from Ciba Specialty Chemicals);2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone(available as IRGACURE 907 from Ciba Specialty Chemicals);2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone(available as IRGACURE 369 from Ciba Specialty Chemicals); and phenylbis(2,4,6-trimethylbenzoyl) phosphine oxide (available as IRGACURE 819from Ciba Specialty Chemicals, N.Y. Other useful photoinitiators includemono- and bis-acylphosphines (available, for example, from CibaSpecialty Chemicals as IRGACURE 1700, IRGACURE 1800, IRGACURE 1850, andDAROCUR 4265).

The binder precursor may comprise an effective amount of at least onethermal initiator; for example, in an amount of from 0.1, 1, or 3percent by weight, up to 5, 7, or even 10 percent by weight, or more.Exemplary thermal free-radical initiators include: azo compounds suchas, for example, 2,2-azo-bisisobutyronitrile, dimethyl2,2′-azobis(isobutyrate), azobis(diphenyl methane),4,4′-azobis-(4-cyanopentanoic acid),(2,2′-azobis(2,4-dimethylvaleronitrile (available as VAZO 52 from E. I.du Pont de Nemours and Co. of Wilmington, Del.); peroxides such as, forexample, benzoyl peroxide, cumyl peroxide, tert-butyl peroxide,cyclohexanone peroxide, glutaric acid peroxide, and dilauryl peroxide;hydrogen peroxide; hydroperoxides such as, for example, tert butylhydroperoxide and cumene hydroperoxide; peracids such as, for example,peracetic acid and perbenzoic acid; potassium persulfate; and peresterssuch as, for example, diisopropyl percarbonate.

In some embodiments, it may be desirable to include one or moremonoethylenically unsaturated free-radically polymerizable compounds inthe binder precursor; for example, to reduce viscosity and/or or reducecrosslink density in the resultant binder. Exemplary monoethylenicallyunsaturated free-radically polymerizable compounds include:mono(meth)acrylates include hexyl (meth)acrylate, 2-ethylhexyl acrylate,isononyl (meth)acrylate, isobornyl (meth)acrylate, phenoxyethyl(meth)acrylate, 2-hydroxyethyl (meth)acrylate, dodecyl (meth)acrylate,methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate,n-butyl (meth)acrylate, n-octyl (meth)acrylate, isobutyl (meth)acrylate,cyclohexyl (meth)acrylate, or octadecyl (meth)acrylate; N-vinylcompounds such as, for example, N-vinylformamide, N-vinylpyrrolidinone,or N-vinylcaprolactam; and combinations thereof.

In some embodiments, the abrasive layer may also include one or moreadditives. The additives can include one or more of an antioxidant, acolorant, a heat and/or light stabilizer, or a filler (the filler havingsubstantially no impact on abrading performance). Accordingly, thebinder may be prepared from a binder precursor comprising the abrasiveparticles, the surfactant, and additives in which the abrasive particlesare dispersed (e.g., as a slurry).

Microstructures

The provided abrasive articles include a flexible backing having opposedfirst and second major surfaces. At least a portion of the second majorsurface of the flexible backing includes replicated microstructureshaving recesses. The replicated microstructures are integral to theflexible backing. By integral it is meant that the replicatedmicrostructures are a part of the flexible backing (e.g., the secondsurface of the flexible backing). The replicated microstructures canextend from a common base (i.e., the flexible backing), be disposed on aseparate backing, and combinations thereof, thereby forming protrusions(distal end of the replicated microstructures) and recesses. In someembodiments, the replicated microstructures can be an extension of theflexible backing material as in the case, e.g., when the replicatedmicrostructures are formed, molded, or embossed, simultaneously with theflexible substrate or grown directly on the flexible substrate.

In some embodiments, the replicated microstructures form recesses in thesecond surface of the flexible backing, i.e., they form a texturedsurface on the flexible backing as a result of a texturizing process,e.g., embossing. Useful flexible backings are presented above andinclude polyester, polycarbonate, polypropylene, polyethylene,cellulose, polyamide, polyimide, polysilicone, andpolytetrafluoroethylene; metal foils including aluminum, copper, tin andbronze; and papers, including densified kraft paper and poly-coatedpaper.

Alternatively, the replicated microstructures can be disposed or formedon a separate backing. The separate backing can be flexible or rigid.The separate backing can then be structurally attached to the secondside of the flexible backing. Any separate backing can be used, howeverthe separate backing needs to not significantly change the overallmodulus of the flexible backing—particularly near the top surface wherethe abrasive elements can be formed. When a separate backing is used,the replicated microstructures on the second backing can be structurallyattached to the flexible backing using a variety of mechanismsincluding, e.g., an adhesive composition (such as a structuraladhesive), sonic welding, heat welding, mechanical fasteners, andcombinations thereof.

The replicated microstructures may have a shape. Examples of such shapesinclude rods, triangles, pyramids, truncated pyramids, cones, truncatedcones, cube corners, cuboids, spheres, or spheroids. The replicatedmicrostructures can have elongated shapes that form ridges. In someembodiments the ridges have the cross-sections of triangles or truncatedtriangles (triangles with a flat top). In other embodiments, the ridgescan have cross-sections that are rectangular, square, or trapezoidal.Alternatively, the replicated microstructures may be randomly shaped.Since the replicated microstructures are replicas, it is typical thatthe three-dimensional shape of the replicated microstructures or thetwo-dimensional cross-sections of the replicated microstructures haveside walls that are at an angle with respect to the plane of the secondmajor surface of the flexible backing that is about 90° or higher. Inother words, the shape of the replicated microstructures does nottypically include an undercut portion that cannot be easily removed froma mold while preserving the features of the replicated microstructures.

As defined herein, “replicated microstructures” are microstructures thatcan be created by a replicated or repeated process. These processesinclude replication processes well known to those of ordinary skill inreplicating microstructures such as, for example, embossing, injectionmolding, cast-and-cure, heat-forming or screen printing.

The replicated microstructures can be formed according to a variety ofmethods including, e.g., molding, extruding, embossing and combinationsthereof. Useful methods of forming microstructure elements aredescribed, e.g., in U.S. Pat. Nos. 5,897,930 (Calhoun et al.); 5,183,597(Lu); 4,588,258 (Hoopman); 4,576,850 (Martens); and 4,374,077 (Kerfeld).Other useful methods for making replicated microstructures include thegeneral methods of making three-dimension abrasive articles disclosed inU.S. Pat. No. 5,958,794 (Bruxvoort et al.). The replicatedmicrostructures can also be made by various other methods. For example,the replicated microstructures can be transferred from a master tool toother media such as a belt or a web of polymeric material, by a cast andcure process from the master tool to form a production tool. Thisproduction tool can then be used to make the microreplicated structurethat includes replicated microstructures using any of the abovementioned methods of replication. Other methods such as electroformingcan be used to copy the master tool.

Another alternate method to make replicated microstructures is todirectly cut or machine the second major surface of the flexible backingmaterial to form the replicated microstructures. Techniques such aschemical etching, laser ablating, bead blasting, or other stochasticsurface modification techniques can be utilized for this purpose. It iscontemplated that when microstructures are directly cut into the secondmajor surface of the flexible backing that they are to be considered“replicated microstructures” if the process is automated to repeatedlydirect a cutting tool, such as an ablative laser, under control of sometype of computer system to produce multiple flexible backings havingreplicated microstructures. Additional disclosure for making flexiblebackings having replicated microstructures can be found, for example, inU.S. Pat. Appl. Publ. No. 2010/0277802 (Gardiner et al.).

Adhesive

The provided abrasive articles and methods include an adhesive thatprovides tack between the flexible backing and a rigid substrate. Insome embodiments, the adhesive can be in contact with a release liner.Any adhesive that can provide tack is suitable for use in the presentdisclosure. The adhesive is contained substantially in the recesses ofthe replicated microstructures. By “substantially contained” it is meantthat the adhesive occupies a substantial volume of the recesses in thereplicated microstructures on the opposed second major surface of theflexible backing. When a rigid substrate is present, the volume of therecesses is the volume defined by the walls of the recesses and therigid substrate. When a rigid substrate is not present the volume of therecesses is the volume defined by the walls of the recesses and a planeacross the distal ends of the replicated microstructures. In theprovided articles and methods, the adhesive can occupy greater thanabout 15 volume percent, greater than about 25 volume percent, or evengreater than about 35 volume percent of the volume of the recesses. Insome embodiments, the volume of the adhesive may be greater than thevolume of the recesses, 110%, 120% or even 130% of the volume of therecesses, typically no more than 150% of the volume of the recesses. Inaddition, the adhesive can just about occupy the volume of the recesses,or can occupy less than about 85 volume percent, less than about 75volume percent, or even less than about 65 volume percent of the volumeof the recesses.

Additionally, “substantially contained” means that the adhesive is notsubstantially present on the distal ends or projections of thereplicated microstructures that form the second major surface of theflexible backing. Typically, when a rigid substrate is present, therigid substrate is in direct contact with at least a portion of thereplicated microstructures. It is important to the operation of theprovided abrasive articles and methods that there is some direct contactbetween the flexible backing and the rigid support in order to bear theload of the work-piece when it is under a load during polishing orlapping. This important feature can resist or prevent crowning oredge-rounding from occurring when the work-piece is polished using theprovided abrasive articles and methods. Typically, the adhesive is notsubstantially present on the distal ends or projections of thereplicated microstructures that form the second major surface of theflexible backing. In some embodiments there is virtually no adhesive onthe distal ends or projections of the replicated microstructures. Inother embodiments, the average amount of adhesive that can be present onthe distal ends or projections of the microstructures is less than about10 μm, less than about 5 μm, or even less than about 3 μm in thickness.It is important that less adhesive is present than that which will alterthe overall mechanical properties and preserve the overall modulus ofthe abrasive article. The load from the work-piece on the abrasivearticle needs to be supported through to the rigid support duringpolishing in order to avoid crowning.

Useful adhesives for securing the abrasive article to the rigidsubstrate are well known to those of ordinary skill in the art. Suitableadhesives include, pressure sensitive adhesives (PSAs), hot meltadhesives and liquid adhesives that can be cured and/or vitrified byordinary means including, radiation curable, e.g. photo curable, UVcurable, E-beam curable, gamma curable; heat curable, moisture curable,and the like. Hot melt adhesives are those adhesives that can flow uponheating at a temperature above the glass and/or melting transitiontemperature of the adhesive. Upon cooling below the transitiontemperature, the hot melt adhesive solidifies. Some hot melt adhesivemay flow upon heating and then solidify due to further curing of theadhesive.

Useful adhesives include, e.g., pressure sensitive adhesives, hot meltadhesives, and glue. Suitable pressure sensitive adhesives include awide variety of pressure sensitive adhesives including, e.g., naturalrubber-based adhesives, (meth)acrylate polymers and copolymers, AB orABA block copolymers of thermoplastic rubbers, e.g., styrene/butadieneor styrene/isoprene block copolymers available under the tradedesignation KRATON (Shell Chemical Co., Houston, Tex.) or polyolefins.Suitable hot melt adhesives include, e.g., polyester, ethylene vinylacetate (EVA), polyamides, epoxies, and combinations thereof. Theadhesive typically has sufficient cohesive strength and peel resistanceto maintain the components of the abrasive article in fixed relation toeach other during use, and should be resistant to chemical degradationunder conditions of use. Exemplary adhesives include epoxy resins suchas those available from 3M Company, St. Paul, Minn., under the tradedesignation SCOTCH-WELD such as 3M SCOTCH-WELD Epoxy Adhesives 1838,2158, 2216, and 3501.

Rigid Substrate

The term “rigid” describes a substrate that is at least self-supporting,i.e., it does not substantially deform under its own weight. By rigid,it is not meant that the substrate is absolutely inflexible. Rigidsubstrates may be deformed or bent under an applied load but offer verylow compressibility. In one embodiment, the rigid substrates comprisematerials having a modulus of rigidity of 1×10⁶ pound per square inch(psi) (7×10⁴ kg/cm²) or greater. In another embodiment, the rigidsubstrates comprise material having a modulus of rigidity of 10×10⁶ psi(7×10⁵ kg/cm²) or greater.

Suitable materials that can function as the rigid substrate includemetals, metal alloys, metal-matrix composites, metalized plastics,inorganic glasses and vitrified organic resins, formed ceramics, andpolymer matrix reinforced composites. The rigid substrate can be aplaten on which the provided abrasive articles can be mounted duringpolishing of a substrate.

Suitable rigid substrate materials include, e.g., organic polymers,inorganic polymers, ceramics, metals, composites of organic polymers,and combinations thereof. Suitable organic polymers can be thermoplasticor thermoset. Suitable thermoplastic materials include polycarbonates,polyesters, polyurethanes, polystyrenes, polyolefins,polyperfluoroolefins, polyvinyl chlorides, and copolymers thereof.Suitable thermosetting polymers include, e.g., epoxies, polyimides,polyesters, and copolymers thereof (i.e., polymers containing at leasttwo different monomers including, e.g., terpolymers and tetrapolymers).

The polymer of the rigid substrate may be reinforced. The reinforcementcan be in the form of fibers or particulate material. Suitable materialsfor use as reinforcement include, e.g., organic or inorganic fibers(e.g., continuous or staple), silicates, e.g., mica or talc,silica-based materials, e.g., sand and quartz, metal particulates,glass, metallic oxides and calcium carbonate, or a combination thereof.

Particularly useful rigid substrates can also include poly(ethyleneterephthalate), polycarbonate, glass fiber reinforced epoxy boards,aluminum, steel, stainless steel. Metal sheets or plates can also beused as the rigid substrate. Suitable metals include, e.g., aluminum,stainless steel, copper, nickel, and chromium. Multi-layer metal platescan also be used, e.g. tin over steel or tin over aluminum.

The provided articles and methods can be further illustrated by thefigures and drawings accompanying this disclosure. FIG. 3 is a schematiccross-section of an embodiment of a provided abrasive article whereinthe microstructures are a part of the second surface of the flexiblebacking and include pyramids or pyramidal ridges. FIG. 3 is anembodiment of abrasive article 300 that includes flexible backing 308.Abrasive layer 302 (that includes abrasive particles retained in abinder) is disposed upon a first major surface of flexible backing 308.On at least a portion of its second major surface, flexible backing 308includes microstructures 306 having recesses. Adhesive 305 is locatedsubstantially in the recesses. In this embodiment, the cross-section ofthe microstructures is V-shaped as defined by the recesses. Work-piece320, which includes a surface to be polished, contacts abrasive layer302, and is moved relative to abrasive article 300 to polish work-piece320. A load P is applied to work-piece 320 as shown in FIG. 2. The loadP is supported by direct contact of at least a portion ofmicrostructures 306 with rigid substrate 312 thereby minimizing, if noteliminating, deformation in the adhesive layer and reducing, if noteliminating crowning or rounding of the edges of work-piece 320.

FIG. 4 is a schematic cross-section of another embodiment of a providedabrasive article. Abrasive article 400 includes flexible backing 408.Abrasive layer 402 (that includes abrasive particles retained in abinder) is disposed upon a first major surface of flexible backing 408.On at least a portion of its second major surface, flexible backing 408includes replicated microstructures 406 having recesses. Adhesive 405 islocated substantially in the recesses. The shape of the microstructuresis identical to that of the embodiment shown in FIG. 3. However, in theembodiment shown in FIG. 4, replicated microstructures 406 have beenformed on a separate backing (not shown) and then integrally bonded toflexible backing 408. Work-piece 420, which includes a surface to bepolished, contacts abrasive layer 402 which is moved relative toabrasive article 400 to polish work-piece 420. A load P is applied towork-piece 420 as shown in FIG. 2. The load P is supported by directcontact of at least a portion of replicated microstructures 406 withrigid substrate 412 thereby minimizing, if not eliminating, deformationin the adhesive layer and reducing, if not eliminating crowning orrounding of the edges of work-piece 420.

FIG. 5 is a schematic cross-section of another embodiment of a providedabrasive article wherein the replicated microstructures includetruncated pyramids or pyramidal ridges. FIG. 5 is an embodiment ofabrasive article 500 that includes flexible backing 508. Abrasive layer502 (that includes abrasive particles retained in a binder, not shown)is disposed upon a first major surface of flexible backing 508. On atleast a portion of its second major surface, flexible backing 508includes replicated microstructures 506 having recesses. Adhesive 505 islocated substantially in the recesses. In this embodiment, thecross-section of the replicated microstructures is truncated V-shaped asdefined by the recesses. The truncated microstructures have a flatplateau that increases the area of contact between flexible backing 508and rigid substrate 512. This provides more load-bearing support duringpolishing. Work-piece 520, which includes a surface to be polished,contacts abrasive layer 502 is moved relative to abrasive article 500 topolish work-piece 520. A load P is applied to work-piece 520 as shown inFIG. 2. The load P is supported by direct contact of at least a portionof replicated microstructures 506 with rigid substrate 512 therebyminimizing, if not eliminating, deformation in the adhesive layer andreducing, if not eliminating crowning or rounding of the edges ofwork-piece 520.

FIG. 6 is a schematic cross-section of yet another embodiment of aprovided abrasive article wherein the replicated microstructure is acuboid or cuboidal ridge. The cross-section of the replicatedmicrostructures is rectangular shaped as defined by the recesses. FIG. 6is an embodiment of abrasive article 600 that includes flexible backing608. Abrasive layer 602 (that includes abrasive particles retained in abinder) is disposed upon a first major surface of flexible backing 608.On at least a portion of its second major surface, flexible backing 608includes replicated microstructures 606 having recesses. Adhesive 605 islocated substantially in recesses. The cuboidal microstructures have aflat plateau that increases the area of contact between flexible backing608 and rigid substrate 612. This provides more load-bearing supportduring polishing. Work-piece 620, which includes a surface to bepolished, contacts abrasive layer 602 which is moved relative toabrasive article 600 to polish work-piece 620. A load P is applied towork-piece 620 as shown in FIG. 2. The load P is supported by directcontact of at least a portion of replicated microstructures 606 withrigid substrate 612 thereby minimizing, if not eliminating, deformationin the adhesive layer and reducing, if not eliminating crowning orrounding of the edges of work-piece 620.

Objects and advantages of this invention are further illustrated by thefollowing examples, but the particular materials and amounts thereofrecited in these examples, as well as other conditions and details,should not be construed to unduly limit this invention.

EXAMPLES Test Methods Lapping Procedure

The simultaneous lapping of three AlTiC coupons, 2.40 cm×0.20 cm×0.5 cm,was conducted using a lapping tool, a Lapmaster model 15 (available fromLapmaster International LLC, Mount Prospect, Ill.). The platen withattached abrasive article was mounted to the base of the tool. A 15 cmdiameter×1 mm AlTiC wafer was mounted to the top surface of the 5.5 inch(14.0 cm) diameter ring of the Lapmaster model 15 using an adhesive,SCOTCHWELD DP100 two part epoxy adhesive (available from 3M Company, St.Paul, Minn.). Three AlTiC coupons were mounted to the AlTiC wafersurface using the same epoxy adhesive. The coupons were mounted along a4.5 mm radius of the wafer, being spaced uniformly, i.e. about 120°apart from one another with their length being perpendicular to theradius. The coupons were mounted such that a 2.40 cm×0.20 cm surface wasmounted to the wafer. Lapping conditions were 20 rpm head rotation, 40rpm platen rotation and a lapping time of 3 hours. During the firsthour, a 2 kg load was applied to the head; during the second hour, a 4kg load was applied and during the third hour, a 6 kg load was applied.The AlTiC coupons rotated in a path that was within the outer diameterand inner diameter of the abrasive covered platen. A lapping fluid wasused, anhydrous ethylene glycol was dripped onto the platen at a rate of0.36 g/min throughout the 3 hour process.

Crown Measurement Procedure

Measurement of the flatness of the AlTiC coupons after lapping wasconducted using a Model P16 Profilometer, (available from KLA-TencorCorporation, Milpitas, Calif.). Four profilometer scans were takenacross the 0.2 cm width of each coupon. The four scans were taken atabout 0.5 cm increments along the length of the coupon. The crown isdefined as the difference between the maximum and minimum height of agiven profilometer scan. The twelve measurements taken from the threecoupons were then averaged to obtain an average crown value.

Fabrication of Backing Having Microstructures with Recess

A steel roll having a width of 25.25 inch (64.1 cm) and a diameter of 12inch (30.5 cm) with copper surface was cut on a diamond turning machineto make a surface having a series of microstructures with recess betweenthe microstructures. A cross-sectional view of microstructure rollsurface, 700, of a small section of roll, 740, is shown in FIG. 7.Recesses, 710, were cut such that they were along the circumference ofthe roll, running perpendicular to roll axis direction, 730, illustratedby dotted two-headed arrow 730. This produced a series of microstructurefeatures, 720, that also ran along the circumference of the roll. Theaverage depth of recesses 710 was 1.3 mils (33.0 μm). The average widthof the base of microstructured features 720 was 1.0 mil (15.4 μm). Theaverage distance between bases of microstructured features 720 was 0.48mils (12.1 μm). The microstructured features 720 were trapezoidal inshape with an average internal angle measured at the top of the featuresof about 110 degrees. After cutting on the diamond turning machine, theroll was degreased with isopropyl alcohol and an alkaline solution wasused to clean the surface. Using an electroless nickel plating process,the copper surface of the steel roll was nickel plated to protect thesurface from oxidation.

This roll was used as the tool in a continuous cast and cure process tomake a microstructure surface, ridges, having recesses on a backing. Inthis cast and cure process, a 23 inch (58.4 cm) wide by 0.005 inch (127microns) thick, polyester film was used as the backing Aphotopolymerizable acrylate resin was applied to the tool, coating awidth of about 20 inches (50.8 cm) along the length of the roll. Theacrylate resin was 75 wt. % aliphatic urethane diacrylate (availableunde the trade designation PHOTOMER 6210 from Cognis Corporation,Cincinnati, Ohio), 24 wt. % 1,6 hexanediol diacrylate (available underthe trade desigantion SR238 from Sartomer Company, Inc., Exton, Pa.) andlwt. % photoinitiator (available under the trade designation LUCIRIN TPOfrom BASF Corp., Charlotte, N.C.). The backing was subsequently appliedto the acrylate coated section of the tool. The acrylate resin was UVcured through the backing while still in the recesses of the rollmicrostructure. The backing was then peeled from the tool. The curedacrylic resin adhered to the backing and released from the tool,producing a microstructure surface. A cross-sectional view, whichcorresponds to a cross-web view, of the backing microstructure is shownin FIG. 8. FIG. 8 shows microstructure backing surface, 800, withrecesses, 810, and microstructure features, 820, on the surface of thebacking, 840. The cross web direction, 830, is indicated. The replicatedmicrostructure surface of the backing has the inverse microstructure asthat of the tool. The average depth of recesses 810 was 1.3 mils (33.0μm). The average width of the base of microstructured features 820 was1.0 mil (15.4 μm). The average distance between bases of microstructuredfeatures 720 was 0.48 mils (12.1 μm). The microstructured features 720were trapezoidal in shape with an average external angle measured at thebottom of the features of about 100 degrees. The microstructures andcorresponding recesses between them followed the down-web direction ofthe web.

Example

A 20 inch (50.8 cm)×20 inch (50.8 cm) sheet of the above backing withmicrostructure surface was taped onto an 18 inch (45.7 cm)×21 inch (53.3cm)×0.625 inch (0.159 cm) aluminum plate, with the microstructuresurface facing the aluminum plate. A solution of 1 g of 3M SCOTCH-WELEpoxy B/A Adhesive (available from the 3M Company, St Paul, Minn.) mixedaccording to the supplier specification and 3 g of methyl ethyl ketone(MEK) was prepared. The solution was poured onto the polyester backingand spread over the surface of the backing using a rubber roller. Thesurface was rolled repeatedly as the solvent evaporated and the epoxyadhesive covered the surface in a uniform manner. Ten grams of abrasivecomposite particles comprising 1 micron diamond/silica 50/50 wt. %prepared according to U.S. Pat. No. 6,645,624 (Adefris et. al.) andsieved to a size of less than 38 micron were poured onto the epoxyadhesive in a line along the edge. The aluminum plate and the coatedbacking were held at a 45° angle and tapped gently to cause theparticles to roll and coat the tacky resin. The procedure was repeateduntil the backing contained a complete coating. The sheet was then heldperpendicular and tapped rigorously to dislodge loose particles. Thebound abrasive was then covered with a sheet of silicone release linerand rolled with a rubber hand roller to press the particles into theepoxy adhesive in a single plane. The coating was allowed to cure for 12hrs at room temperature and then an additional 2 hrs at 70° C.

The abrasive layer was then spray coated with a securing size coating ofresin. The size coating resin solution consisted of 4 g of a phenoxyresin solution, 30 wt. % in 2-butanone (available under the tradedesignation of YP-50S from Tohto Kasei Co. Lt. Inabata America Corp, NY,N.Y.); 2.3 g of a polyester polyurethane resin solution, 35 wt. % in MEK(synthesized internally from neopentyl glycol, 21 wt. %, polycaprolactone, 29 wt. %, and a methylene diisocyanate 50 wt. %); 1.1 g ofpolymeric isocyanate (available under the trade designation Mondur MRSfrom Bayer Chemical, Pittsburgh, Pa.); 40 g MEK and 10 g ofcyclohexanone. The size coating resin solution was placed in an aerosolcontainer. The abrasive surface was sprayed with the size coatingsolution in a well ventilated hood for about 60 seconds or until thesurface looked wet. The aluminum plate and abrasive article were thenheated in an oven at 70° C. for 17 hrs. After cooling, the film withmicrostructure was turned over, so that the abrasive surface contactedthe aluminum plate and the microstructure surface was exposed. A layerof non-crosslinked, acrylate based, pressure sensitive adhesive having a0.0009 inch (22.9 micron) nominal thickness, coated on a siliconizedkraft paper release liner, was then hand laminated to the microstructuresurface of the backing using a rubber roller. The release liner of theabrasive article was removed and the abrasive article was hand laminatedusing a rubber roller to a flat annular shaped, aluminum platen having a16 inch (40.6 cm) outside diameter, an 8 inch (20.3 cm) inside diameterand a 1.5 inch (3.8 cm) thickness, which was fabricated using standardCNC cutting techniques.

The platen with the abrasive article was then place abrasive face downonto a quartz sheet, 23 inch (58.4 cm)×18 inch (45.7 cm)×⅜ inch (0.95cm). An identical platen, weighing 10.7 kg, was placed on top of thefirst platen with attached abrasive and the entire stack was heated inan oven for 70° C. for 48 hrs. The stack was removed from the oven, the2^(nd) platen was removed from the stack and the platen with attachedabrasive article was allowed to cool while the abrasive was still incontact with the quartz plate. The abrasive article was trimmed with arazor blade to fit the dimensions of the platen. Following the lappingprocedure and the crown measurement procedure described above, theaverage crown of the three AlTiC coupons was 0.9 micro-inches (0.0229μm).

Various modifications and alterations to this invention will becomeapparent to those skilled in the art without departing from the scopeand spirit of this invention. It should be understood that thisinvention is not intended to be unduly limited by the illustrativeembodiments and examples set forth herein and that such examples andembodiments are presented by way of example only with the scope of theinvention intended to be limited only by the claims set forth herein asfollows. All references cited in this disclosure are herein incorporatedby reference in their entirety.

Following are exemplary embodiments of an abrasive article withreplicated microstructured backing and method of using same according toaspects of the present invention.

Embodiment 1 is an abrasive article comprising: a flexible backinghaving opposed first and second major surfaces, wherein at least aportion the second major surface of the flexible backing includesreplicated microstructures having recesses; an abrasive layer comprisinga plurality of abrasive particles retained in at least one binder, theabrasive layer disposed on the first major surface of the flexiblebacking; and an adhesive, wherein the adhesive is containedsubstantially in the recesses of the replicated microstructures.

Embodiment 2 is an abrasive article according to embodiment 1, furthercomprising: a rigid substrate in contact with at least a portion of thereplicated microstructures.

Embodiment 3 is an abrasive article according to embodiment 1, furthercomprising: a release liner in contact with at least a portion of theadhesive.

Embodiment 4 is an abrasive article according to embodiment 1, whereinthe flexible backing is selected from the group consisting of densifiedkraft paper, poly-coated paper, metal foils, and polymeric substrate.

Embodiment 5 is an abrasive article according to embodiment 4, whereinthe metal foils are selected from aluminum, copper, tin, and bronze.

Embodiment 6 is an abrasive article according to embodiment 4, whereinthe polymeric substrate is selected from the group consisting ofpolyester, polycarbonate, polypropylene, polyethylene, cellulose,polyamide, polyimide, polysilicone, and polytetrafluoroethylene.

Embodiment 7 is an abrasive article according to embodiment 1, whereinthe abrasive particles are selected from the group consisting of fusedaluminum oxide, heat treated aluminum oxide, white fused aluminum oxide,black silicon carbide, green silicone carbide, titanium diboride, boroncarbide, tungsten carbide, titanium carbide, diamond, silica, ironoxide, chromia, ceria, zirconia, titania, silicates, tin oxide, cubicboron nitride, garnet, fused alumina zirconia, sol gel abrasiveparticles, abrasive agglomerates, metal-based particulates, andcombinations thereof.

Embodiment 8 is an abrasive article according to embodiment 1, whereinthe flexible backing has a Young's modulus of greater than about 0.5GPa.

Embodiment 9 is an abrasive article according to embodiment 8, whereinthe flexible backing has a Young's modulus of greater than about 2.0GPa.

Embodiment 10 is an abrasive article according to embodiment 1, whereinthe replicated microstructures have a shape that comprises rods,triangles, pyramids, truncated pyramids, cones, truncated cones, cubecorners, cuboids, spheres, or spheroids.

Embodiment 11 is an abrasive article according to embodiment 1, whereinthe replicated microstructures have a shape that comprises ridges.

Embodiment 12 is an abrasive article according to embodiment 1, whereinthe adhesive is selected from the group consisting of pressure-sensitiveadhesives, hot melt adhesives and curable liquid adhesives.

Embodiment 13 is an abrasive article according to embodiment 1, whereinthe adhesive occupies greater than about 25 volume percent and less thanabout 120 volume percent of the volume of the recesses of the replicatedmicrostructures.

Embodiment 14 is a method of polishing comprising: providing awork-piece to be polished; contacting the work-piece with an abrasivearticle comprising: a flexible backing having opposed first and secondmajor surfaces, wherein at least a portion the second major surface ofthe flexible backing includes replicated microstructures havingrecesses; an abrasive layer comprising a plurality of abrasive particlesretained in at least one binder, the abrasive layer disposed on thefirst major surface of the flexible backing; an adhesive; and a rigidsubstrate in contact with at least a portion of the replicatedmicrostructures, wherein the adhesive is contained substantially in therecesses of the replicated microstructures; and moving the abrasivearticle relative to the work-piece.

Embodiment 15 is a method of polishing according to embodiment 14,wherein the abrasive particles are selected from the group consisting offused aluminum oxide, heat treated aluminum oxide, white fused aluminumoxide, black silicon carbide, green silicone carbide, titanium diboride,boron carbide, tungsten carbide, titanium carbide, diamond, silica, ironoxide, chromia, ceria, zirconia, titania, silicates, tin oxide, cubicboron nitride, garnet, fused alumina zirconia, sol gel abrasiveparticles, abrasive agglomerates, metal-based particulates, andcombinations thereof.

Embodiment 16 is a method of polishing according to embodiment 14,wherein the replicated microstructures have a shape that comprises rods,triangles, pyramids, truncated pyramids, cones, truncated cones, cubecorners, cuboids, spheres, or spheroids.

Embodiment 17 is a method of polishing according to embodiment 14,wherein the replicated microstructures have a shape that comprisesridges.

Embodiment 18 is a method of polishing according to embodiment 14,wherein the adhesive is selected from the group consisting ofpressure-sensitive adhesives, hot melt adhesives and curable liquidadhesives.

Embodiment 19 is a method of polishing according to embodiment 14,wherein the adhesive occupies greater than about 25 volume percent andless than about 120 volume percent of the volume of the recesses of thereplicated microstructures.

Embodiment 20 is a method of polishing according to embodiment 14,further comprising a release liner disposed on the adhesive.

Although specific embodiments have been illustrated and described hereinfor purposes of description of the preferred embodiment, it will beappreciated by those of ordinary skill in the art that a wide variety ofalternate and/or equivalent implementations calculated to achieve thesame purposes may be substituted for the specific embodiments shown anddescribed without departing from the scope of the present invention.Those with skill in the mechanical, electro-mechanical, and electricalarts will readily appreciate that the present invention may beimplemented in a very wide variety of embodiments. This application isintended to cover any adoptions or variations of the preferredembodiments discussed herein. Therefore, it is manifestly intended thatthis invention be limited only by the claims and the equivalentsthereof.

What is claimed is:
 1. An abrasive article comprising: a flexiblebacking having opposed first and second major surfaces, wherein at leasta portion the second major surface of the flexible backing includesreplicated microstructures having recesses; an abrasive layer comprisinga plurality of abrasive particles retained in at least one binder, theabrasive layer disposed on the first major surface of the flexiblebacking; and an adhesive, wherein the adhesive is containedsubstantially in the recesses of the replicated microstructures.
 2. Anabrasive article according to claim 1, further comprising: a rigidsubstrate in contact with at least a portion of the replicatedmicrostructures.
 3. An abrasive article according to claim 1, furthercomprising: a release liner in contact with at least a portion of theadhesive.
 4. An abrasive article according to claim 1, wherein theflexible backing is selected from the group consisting of densifiedkraft paper, poly-coated paper, metal foils, and polymeric substrate. 5.An abrasive article according to claim 4, wherein the metal foils areselected from aluminum, copper, tin, and bronze.
 6. An abrasive articleaccording to claim 4, wherein the polymeric substrate is selected fromthe group consisting of polyester, polycarbonate, polypropylene,polyethylene, cellulose, polyamide, polyimide, polysilicone, andpolytetrafluoroethylene.
 7. An abrasive article according to claim 1,wherein the abrasive particles are selected from the group consisting offused aluminum oxide, heat treated aluminum oxide, white fused aluminumoxide, black silicon carbide, green silicone carbide, titanium diboride,boron carbide, tungsten carbide, titanium carbide, diamond, silica, ironoxide, chromia, ceria, zirconia, titania, silicates, tin oxide, cubicboron nitride, garnet, fused alumina zirconia, sol gel abrasiveparticles, abrasive agglomerates, metal-based particulates, andcombinations thereof.
 8. An abrasive article according to claim 1,wherein the flexible backing has a Young's modulus of greater than about0.5 GPa.
 9. An abrasive article according to claim 8, wherein theflexible backing has a Young's modulus of greater than about 2.0 GPa.10. An abrasive article according to claim 1, wherein the replicatedmicrostructures have a shape that comprises rods, triangles, pyramids,truncated pyramids, cones, truncated cones, cube corners, cuboids,spheres, or spheroids.
 11. An abrasive article according to claim 1,wherein the replicated microstructures have a shape that comprisesridges.
 12. An abrasive article according to claim 1, wherein theadhesive is selected from the group consisting of pressure-sensitiveadhesives, hot melt adhesives and curable liquid adhesives.
 13. Anabrasive article according to claim 1, wherein the adhesive occupiesgreater than about 25 volume percent and less than about 120 volumepercent of the volume of the recesses of the replicated microstructures.14. A method of polishing comprising: providing a work-piece to bepolished; contacting the work-piece with an abrasive article comprising:a flexible backing having opposed first and second major surfaces,wherein at least a portion the second major surface of the flexiblebacking includes replicated microstructures having recesses; an abrasivelayer comprising a plurality of abrasive particles retained in at leastone binder, the abrasive layer disposed on the first major surface ofthe flexible backing; an adhesive; and a rigid substrate in contact withat least a portion of the replicated microstructures, wherein theadhesive is contained substantially in the recesses of the replicatedmicrostructures; and moving the abrasive article relative to thework-piece.
 15. A method of polishing according to claim 14, wherein theabrasive particles are selected from the group consisting of fusedaluminum oxide, heat treated aluminum oxide, white fused aluminum oxide,black silicon carbide, green silicone carbide, titanium diboride, boroncarbide, tungsten carbide, titanium carbide, diamond, silica, ironoxide, chromia, ceria, zirconia, titania, silicates, tin oxide, cubicboron nitride, garnet, fused alumina zirconia, sol gel abrasiveparticles, abrasive agglomerates, metal-based particulates, andcombinations thereof.
 16. A method of polishing according to claim 14,wherein the replicated microstructures have a shape that comprises rods,triangles, pyramids, truncated pyramids, cones, truncated cones, cubecorners, cuboids, spheres, or spheroids.
 17. A method of polishingaccording to claim 14, wherein the replicated microstructures have ashape that comprises ridges.
 18. A method of polishing according toclaim 14, wherein the adhesive is selected from the group consisting ofpressure-sensitive adhesives, hot melt adhesives and curable liquidadhesives.
 19. A method of polishing according to claim 14, wherein theadhesive occupies greater than about 25 volume percent and less thanabout 120 volume percent of the volume of the recesses of the replicatedmicrostructures.
 20. A method of polishing according to claim 14,further comprising a release liner disposed on the adhesive.